1. Wanda and Pietro used to be married. Their lives were also plagued by a giant monster creature, so the twincest wasn't really the first thing on their minds.
2. Natasha and Steve were old high school buddies who stole the answers to the SATs. He was the goody-goody honor student and she was the alt chick just itching for graduation.
3. They fell for each other after college when she was working as a nanny on the Upper East Side and he was renting the apartment downstairs.
4. Before joining with Tony, Pepper was working as a stewardess. She was going through a pink leopard phase when she fell for Bruce, who had a rad boat at the time.
5. The two met again when Bruce was in recovery for sex addiction.
6. Bruce also spent some time falling in love with a ghost.
7. Natasha and Fury took a detour as supervillains, Fury working as a psychotic coroner and Nat as his scientist accomplice.
8. Sam was once a gay politician who tried to marry the girl Steve was in love with, who also used to date Peter Quill. They had a brunch once to hash out all their former conflicts and the bro code of it all.
(The woman who played that girl is also Chris Pratt's wife in real life, Anna Faris. 2011's What's Your Number is a twisted web.)